/* DannyNiu/NJF, 2021-06-21. Public Domain. */

#include "sm4.h"

// see 2025-02-23 note towards the beginning of "1-symm/rijndael.c".
#if defined(DEF_INC_FROM_NI) == defined(IntrinSelf)

#include "../0-datum/endian.h"
#include "../0-datum/sbox.c.h"

// Spec to code name table:
// F:   Rnd_F
// T:   Pmt_T0
// T':  Pmt_t1
// L:   Lin0
// L':  Lin1
// tau: tau

static inline uint32_t Rnd_F(
    uint32_t X_0,
    uint32_t X_1,
    uint32_t X_2,
    uint32_t X_3,
    uint32_t rk);

static inline uint32_t Pmt_T0(uint32_t x);
static inline uint32_t Pmt_T1(uint32_t x);

static inline uint32_t Lin0(uint32_t x);
static inline uint32_t Lin1(uint32_t x);
static inline uint32_t tau(uint32_t x);

#define CALC(b,i) (uint32_t)b*0x01010101, (uint32_t)i*0x01010101

static const alignas(1024) uint32_t wsbox_table[512] = SBOX_WIDENER(
    CALC,
    0xD6, 0x90, 0xE9, 0xFE, 0xCC, 0xE1, 0x3D, 0xB7, 0x16, 0xB6, 0x14, 0xC2, 0x28, 0xFB, 0x2C, 0x05,
    0x2B, 0x67, 0x9A, 0x76, 0x2A, 0xBE, 0x04, 0xC3, 0xAA, 0x44, 0x13, 0x26, 0x49, 0x86, 0x06, 0x99,
    0x9C, 0x42, 0x50, 0xF4, 0x91, 0xEF, 0x98, 0x7A, 0x33, 0x54, 0x0B, 0x43, 0xED, 0xCF, 0xAC, 0x62,
    0xE4, 0xB3, 0x1C, 0xA9, 0xC9, 0x08, 0xE8, 0x95, 0x80, 0xDF, 0x94, 0xFA, 0x75, 0x8F, 0x3F, 0xA6,
    0x47, 0x07, 0xA7, 0xFC, 0xF3, 0x73, 0x17, 0xBA, 0x83, 0x59, 0x3C, 0x19, 0xE6, 0x85, 0x4F, 0xA8,
    0x68, 0x6B, 0x81, 0xB2, 0x71, 0x64, 0xDA, 0x8B, 0xF8, 0xEB, 0x0F, 0x4B, 0x70, 0x56, 0x9D, 0x35,
    0x1E, 0x24, 0x0E, 0x5E, 0x63, 0x58, 0xD1, 0xA2, 0x25, 0x22, 0x7C, 0x3B, 0x01, 0x21, 0x78, 0x87,
    0xD4, 0x00, 0x46, 0x57, 0x9F, 0xD3, 0x27, 0x52, 0x4C, 0x36, 0x02, 0xE7, 0xA0, 0xC4, 0xC8, 0x9E,
    0xEA, 0xBF, 0x8A, 0xD2, 0x40, 0xC7, 0x38, 0xB5, 0xA3, 0xF7, 0xF2, 0xCE, 0xF9, 0x61, 0x15, 0xA1,
    0xE0, 0xAE, 0x5D, 0xA4, 0x9B, 0x34, 0x1A, 0x55, 0xAD, 0x93, 0x32, 0x30, 0xF5, 0x8C, 0xB1, 0xE3,
    0x1D, 0xF6, 0xE2, 0x2E, 0x82, 0x66, 0xCA, 0x60, 0xC0, 0x29, 0x23, 0xAB, 0x0D, 0x53, 0x4E, 0x6F,
    0xD5, 0xDB, 0x37, 0x45, 0xDE, 0xFD, 0x8E, 0x2F, 0x03, 0xFF, 0x6A, 0x72, 0x6D, 0x6C, 0x5B, 0x51,
    0x8D, 0x1B, 0xAF, 0x92, 0xBB, 0xDD, 0xBC, 0x7F, 0x11, 0xD9, 0x5C, 0x41, 0x1F, 0x10, 0x5A, 0xD8,
    0x0A, 0xC1, 0x31, 0x88, 0xA5, 0xCD, 0x7B, 0xBD, 0x2D, 0x74, 0xD0, 0x12, 0xB8, 0xE5, 0xB4, 0xB0,
    0x89, 0x69, 0x97, 0x4A, 0x0C, 0x96, 0x77, 0x7E, 0x65, 0xB9, 0xF1, 0x09, 0xC5, 0x6E, 0xC6, 0x84,
    0x18, 0xF0, 0x7D, 0xEC, 0x3A, 0xDC, 0x4D, 0x20, 0x79, 0xEE, 0x5F, 0x3E, 0xD7, 0xCB, 0x39, 0x48);

static inline uint32_t Rnd_F(
    uint32_t X_0,
    uint32_t X_1,
    uint32_t X_2,
    uint32_t X_3,
    uint32_t rk)
{
    return X_0 ^ Pmt_T0(X_1 ^ X_2 ^ X_3 ^ rk);
}

static inline uint32_t Pmt_T0(uint32_t x)
{
    return Lin0(tau(x));
}

static inline uint32_t Pmt_T1(uint32_t x)
{
    return Lin1(tau(x));
}

static inline uint32_t tau(uint32_t x)
{
    return wsbox(x, wsbox_table);
}

static inline uint32_t Lin0(uint32_t B)
{
    return
        B                   ^
        (B <<  2 | B >> 30) ^
        (B << 10 | B >> 22) ^
        (B << 18 | B >> 14) ^
        (B << 24 | B >>  8);
}

static inline uint32_t Lin1(uint32_t B)
{
    return B ^ (B << 13 | B >> 19) ^ (B << 23 | B >> 9);
}

static void SM4Feistel(
    void const *in, void *out,
    void const *restrict w, int rev)
{
    uint32_t const *rk = w;
    uint32_t X[4];
    unsigned i;

    for(i=0; i<4; i++)
    {
        X[i] = ((uint32_t const *)in)[i];
        X[i] = be32toh(X[i]);
    }

    for(i=0; i<32; i++)
    {
        X[i & 3] = Rnd_F(
            X[(i + 0) & 3],
            X[(i + 1) & 3],
            X[(i + 2) & 3],
            X[(i + 3) & 3],
            rk[rev ? 31 - i : i]);
    }

    for(i=0; i<4; i++) ((uint32_t *)out)[i] = htobe32(X[3 - i]);
}

void SM4Encrypt(void const *in, void *out, void const *restrict w)
{
    SM4Feistel(in, out, w, false);
}

void SM4Decrypt(void const *in, void *out, void const *restrict w)
{
    SM4Feistel(in, out, w, true);
}

static const uint32_t FK[4] = {
    0xA3B1BAC6, 0x56AA3350, 0x677D9197, 0xB27022DC,
};

static const uint32_t CK[32] = {
    0x00070E15, 0x1C232A31, 0x383F464D, 0x545B6269,
    0x70777E85, 0x8C939AA1, 0xA8AFB6BD, 0xC4CBD2D9,
    0xE0E7EEF5, 0xFC030A11, 0x181F262D, 0x343B4249,
    0x50575E65, 0x6C737A81, 0x888F969D, 0xA4ABB2B9,
    0xC0C7CED5, 0xDCE3EAF1, 0xF8FF060D, 0x141B2229,
    0x30373E45, 0x4C535A61, 0x686F767D, 0x848B9299,
    0xA0A7AEB5, 0xBCC3CAD1, 0xD8DFE6ED, 0xF4FB0209,
    0x10171E25, 0x2C333A41, 0x484F565D, 0x646B7279,
};

void SM4KeySched(void const *restrict key, void *restrict w)
{
    uint32_t const *MK = key;
    uint32_t K[4];
    uint32_t *rk = w;
    unsigned i;

    for(i=0; i<4; i++) K[i] = be32toh(MK[i]) ^ FK[i];

    for(i=0; i<32; i++)
    {
        rk[i] = K[i & 3] ^= Pmt_T1(
            K[(i + 1) & 3] ^ K[(i + 2) & 3] ^ K[(i + 3) & 3] ^
            CK[i]);
    }
}

IntPtr iSM4(int q) { return cSM4(q); }

#endif /* duplicate symbol definitions guard. */
